The present invention relates to an optical crossconnect apparatus, and more particularly to an optical crossconnect apparatus having a failure recovery function through the use of in-channel signals.
Because of the explosive growth of traffic along with the diffusion of the Internet, as well as the development of optical switching technology such as a MEMS based optical switch, there is a demand for large-scale optical crossconnect apparatus to be put into practical use.
It is important for the optical crossconnect apparatus to have an optical path setting function for managing a wavelength as a path and a failure recovery function for network failure.
In Japanese Patent Publication Laid-Open No. 2004-297238, there is described an optical crossconnect apparatus that helps relieve a line using overhead information of the OTN (Optical Transport Network) frame. This optical crossconnect apparatus can forward in-band control signals (in-channel control signals), which makes it possible to provide path failover upon occurrence of a failure by controlling an adjacent optical crossconnect apparatus. Meanwhile, for the above-described optical crossconnect apparatus, it is necessary to perform OEO conversion (optical-electrical-optical conversion) twice per node, and which tends to increase cost.
Further, in JP-A No. 2003-209863 and JP-A No. 2003-339064, there are described optical crossconnect apparatuses that connect the input/output of a wavelength conversion repeater capable of converting to any wavelength, to an optical switch, and can select the route and wavelength channel for the use of the wavelength conversion repeater. These optical crossconnect apparatuses make it possible to reduce the number of OEO conversions to less than or equal to once per node, when using the OEO conversion for wavelength conversion. However, the above-described optical crossconnect apparatus is provided with an optical switch between a demultiplexer and the wavelength conversion repeater, and cannot receive in-channel control signals transmitted to the wavelength conversion repeater of the own node from the wavelength conversion repeater of another node. In addition, the above-described optical crossconnect apparatus is provided with the optical switch between the wavelength conversion repeater and a multiplexer, and cannot transmit the in-channel control signals from the wavelength conversion repeater of the own node to the wavelength conversion repeater of another node.
Incidentally, the specification of U.S. Pat. No. 2003/0198227 is the US counterpart of JP-A No. 2003-339064.
The present invention provides an optical crossconnect apparatus capable of using in-channel control signals for switching control of optical crossconnect paths so that the optical path can avoid the failed part upon occurrence of a failure, improving efficiency in use of a tunable wavelength conversion repeater shared for backup purposes, while reducing the number of OEO conversions.